This invention relates generally to information systems, and more particularly to a method and apparatus for managing information retention.
To limit the amount of information that is maintained in an information system, many companies implement policies (often referred to as information retention policies) under which information sets are systematically deleted from the system. These policies set forth criteria for determining if and when an information set is to be deleted, and are often time-based, such that an information set is deleted after having been in the system for a certain amount of time, or condition-based, such that an information set is deleted after a certain condition has been satisfied, or a combination of both. For example, a set of information may be deleted if it has been in the system for a certain amount of time AND it has not been accessed within a certain period of time. By systematically deleting information sets from the system, the system is maintained at a reasonable size. This helps to limit the amount of storage required to implement the system, and the effort needed to maintain the system.
Typically, an information retention policy is enforced by deleting from the system information sets which have been determined under the retention policy as being eligible for deletion. An information set may be deleted by removing references to the information set, thereby rendering the information set inaccessible, or by overwriting the information set with new information, or both. While removing an information set from a system by way of deletion is sound in principle, it is difficult to implement in practice. One of the main problems with the deletion method is that in order to delete an instance of an information set, it is first necessary to find it. If there are multiple copies of an information set (as is often the case if the system is large or distributed or if backup copies are made), it is necessary to find and to delete all copies of the information set before the information set is completely removed from the information system. For a large information system, it can be a tedious, daunting, and sometimes impossible task to find all copies of an information set. As a result, stray copies of an information set often linger in the system even after the information set has supposedly been deleted. These stray copies can seriously undermine the effectiveness of the retention policy. As this discussion illustrates, the current methodology for enforcing information retention policies leaves much to be desired. As a result, an improved mechanism for managing information retention is needed.